1. Field of the Invention
This disclosure relates to an interval securing member to be used for an image forming apparatus, and a developing apparatus and a process cartridge having the interval securing member.
The term “image forming apparatus” used here includes electrophotographic copying machines, electrophotographic printers (for example, laser beam printers, LED printers, and the like), and facsimile apparatuses configured to form images on recording media using, for example, an electrophotographic image forming system.
2. Description of the Related Art
In the related art, in the image forming apparatus using the electrophotographic image forming process, in order to restrict a distance between a photosensitive drum (an image bearing member) and a developing roller (a developer bearing member) to be constant, an interval securing member referred to as a SD roller is provided at an end of the developing roller (see Japanese Patent Laid-Open No. 8-305106 and Japanese Patent Laid-Open No. 6-230665).
The SD roller is clamped between the photosensitive drum and the developing roller, and restricts the distance between the photosensitive drum and the developing roller to be constant by the thickness of the SD roller.
The photosensitive drum and the developing roller rotates so that peripheral surfaces thereof move in the same direction at opposing portions, and the SD roller maintains an interval between the photosensitive drum and the developing roller while being rotated by the photosensitive drum or the developing roller.
As the developing roller rotates, the portion of the SD roller that comes into contact with the photosensitive drum changes. If the SD roller has a portion which is not uniform in radius, when the portion contacts with the photosensitive drum, the interval between the photosensitive drum and the developing roller varies, and an image may be affected thereby.
Therefore, the dimensions of the SD roller are precisely controlled so as to have a uniform radius over the entire periphery thereof.
The image forming apparatus using the SD roller of the related art satisfies an image quality presently required. However, since higher image quality is required in recent years, the distance between the photosensitive drum and the developing roller needs to be maintained further precisely in the future.
This disclosure provides an interval securing member that has a simple structure and is not moved by rotations of the developer bearing member and the image bearing member in the direction of the rotations during an image-forming period. Accordingly, this disclosure is provided to maintain the distance between the image bearing member and the developer bearing member stably.